1. Field of the Invention
The present invention relates to a flip-chip bonding method and apparatus.
2. Prior Art
A semiconductor device with a daisy-chain type of pattern, for example, is produced by directly bonding a chip to a substrate and then injecting a sealant composed of a resin or the like between the chip and substrate. On the substrate side, a pattern and pads are formed on a printed substrate or ceramic substrate; and on the chip side, pads are formed on a silicon chip. Since the substrate and chip are opaque, the pattern and pads of the substrate and chip cannot be observed by optical transmission.
A daisy-chain type of pattern is known from Japanese Patent Application Laid-Open (Kokai) H5-29546, for example, and with this type of pattern, if the pad groups provided on the substrate and the pad groups provided on the chip are superimposed in the bonding of the substrate and chip, then electrical conduction will be achieved between each pad of the substrate and the corresponding pad of the chip, thus forming a single electrical path between two electrical conduction confirmation terminals provided to the substrate.
The bonding of a semiconductor device with a daisy-chain pattern is carried out by the steps illustrated in FIG. 14.
As shown in FIG. 14(a), a substrate 1 is set so that its pattern and pads face up, the substrate 1 being supported on a substrate chuck 2; a chip 3 is set so that its pattern and pads are facing down, the chip 3 being supported by a chip chuck 4; and further the chip 3 is disposed above the substrate 1.
Next, as shown in FIG. 14(b), an optical probe 5 having upper and lower detection components on its top and bottom surfaces, respectively, is inserted in the direction of arrow A between the substrate 1 and the chip 3, and the respective patterns and pads of the substrate 1 and chip 3 are detected by an optical probe 5. The substrate chuck 2 and the chip chuck 4 are moved in relation to each other so as to level and position the substrate 1 and the chip 3.
After this, as shown in FIG. 14(c), the optical probe 5 is moved in the direction of arrow B, after which the chip chuck 4 is lowered and the substrate 1 is bonded with the chip 3 as shown in FIG. 14(d). Then, as shown in FIG. 14(e), the substrate chuck 2 is lowered to complete the bonding. Examples of this optical probe 5 are disclosed in Japanese Patent Application Publication (Kokoku) H6-28272, for instance.
Confirmation of the bonding precision of a semiconductor device such as this can be accomplished by two methods. In the first method, a substrate 1 and a chip 3 that are actual products are bonded and checked under an infrared microscope after bonding, or they are checked by tearing off the chip 3 in a destructive test. Here, observing the components under an infrared microscope is based on the fact that the chip 3 is composed of silicon and infrared rays pass through silicon, so a transmission image of the chip 3 is obtained. In the second method, the substrate or the chip is bonded to a precision confirmation element composed of transparent glass, this bonded product is taken out of the bonding apparatus, and then the positional shift of the pattern and pads is measured from the glass side with a length measuring machine.
Thus, since either a bonded actual product or a precision confirmation element has to be taken out of the bonding apparatus for measurement, the bonding precision cannot be confirmed rapidly. If there is any positional shift, the mechanism of the optical probe 5 or the drive components of the substrate chuck 2 and chip chuck 4 are adjusted. Of these adjustments, the adjustment of the mechanism of the optical probe 5, for instance, is performed because, as disclosed in Japanese Patent Application Publication (Kokoku) H6-28272, the images detected by upper and lower detection components are each captured by an imaging element via separate optical systems; and since there are thus two optical systems, positional discrepancy occurs if the two systems are not aligned; as a result, the optical systems need to be adjusted.
Also, since there is no daisy-chain pattern with a conventional precision confirmation element that is transparent on just one side, the bonded precision confirmation semiconductor device is opaque, and electrical conduction cannot be confirmed. Accordingly, an actual semiconductor device, which is an opaque finished product, needs to be inspected in order to confirm electrical conduction, and the confirmation of bonding precision and the confirmation of electrical conduction have to be carried out separately. Also, because it is opaque, the interior of the bonded component cannot be checked, and it is impossible to observe the injection state after a sealant is injected between the substrate and the chip in a subsequent step.